Alkylation of phenols



Patented July 26, 1949 2,477,091 'ALKYLA'rIoN or PHENOLS Robert H. Rosenwald, Western Springs, 111., assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware H No Drawing. Application April 16, 1947,

Serial No. 741,943

14 Claims: (Cl. 260-612) This invention relates to the reaction of a phenolic compound with an alkylating agent. It is more particularly concerned with the O-alkylation of phenolic compounds by a method which comprises reacting a phenol with an alkylating agent at certain temperature conditions in the presence of a carboxylic acid alkylation catalyst.

A number of efiicient processes for the nuclear alkylation of aromatic compounds containing a hydroxyl group are known to those skilled in the art. However, it frequently is desirable to O-alkylate compounds of this type in order to produce aromatic ethers for use in the preparation of inhibitors and the like. I have discovered an efficient method of accomplishing this result.

In one embodiment my invention relates to an O-alkylation process which comprises contacting a phenolic compound with an alkylating agent at an alkylating temperature below about 150 C. in the presence of a carboxylic acid alkylation catalyst.

In a more specific embodiment my invention relates to an O-alkylation process which comprises contacting a phenolic compound with an alkylating agent at an alkylating temperature below about 150 C. in the presence of a chloroacetic acid alkylation catalyst.

In another specific embodiment my invention relates to an O-alkylation process which comprises contacting a phenolic compound with an alkylating agent at an alkylating temperature below about 150 C. in the presence of a nitrobenzoic acid alkylation catalyst.

Phenolic compounds that may be reacted with alkylating agents in accordance with the process of this invention include materials such as phenol, hydroquinone, catechol, hydroxyquinol, guaiacol, para-methoxyphenol, para-ethoxyphenol, Z-tertiary butyl-4-methoxyphenol, cresol, and the like.

The alkylating agents utilizable in this process includesubstances capable of yielding an alkyl group at the conditions of operation employed in the process. Examples of such substances are olefins, both normally aseous and normally liquid, cycloparafiins containing less than 5 carbon atoms in the ring, mercaptans, mineral acid esters such as alkyl halides and alkoxy compounds of the class consisting of aliphatic alcohols, ethers, and esters of carboxylic acids. In general olefins and alcohols are the most useful alkylating agents in my process. Ethylene is difiicultly reactable with phenols and for this reason its use is limited.

The catalysts that may be used in this process consist of carboxylic acids that promote the O-alkylation of phenols. Such catalysts include mono-, di-, and trichloroacetic acids, mono di-, and tribromoacetic acids, mono-, di-, and trinitrobenzoic acids, oxalic acid, formicacid, propionic acid, and the like.

The process of my invention may be carried out in batch operation by placing a quantity of the catalyst in a reactor equipped with astirring device, adding the phenolic compound, heating or cooling to the reaction temperature, slowly adding the alkylating agent while mixing the contents of the reactor, and recovering the product. However, the preferred method of operation is of the continuous type. In one mode of continuous operation, the catalyst is continuously charged to a reactor together with a phenol and the alkylating agent. The reactor effluent is continuously passed to a separation zone wherein the products are recovered, from the unconverted reactants and the catalyst.

The process of this invention is conducted at temperatures below about C. Above this temperature, substantially no O-alkylatio'n is obtained. Thelower temperature limit is governed by the reactivity of the reactants and by the activity of the catalyst. Usually the reaction is too slow to be economically feasible if the temperature is below about -2 0 C.

Although some-reaction is obtained when the reactants and the catalyst are in the vapor phase, better results are obtained when they are in the liquid phase. Consequently, the pressure will be chosen accordingly.

The contact time may be in the range of from about 3 minutes to about 3 hours.

A molecular excess ofthe phenolic compound over the alkylating agent in the reaction zone promotes reaction between the phenol and the alkylating agent and suppresses undesirable side reactions. H a I The following examplesare giv'ento illustrate my invention .but they are not introduced with the intention of unduly limiting the generally broad scope. of said invention.

Examples clave was cooled and the material contained there-.

in was removed and extracted with caustic to separate the unreacted phenol. The remaining product was then analyzed for ethers. The reacw I group; 7 t It willbe QQalliylptlonwas obtained .3 tion temperature in all of the examples except No. 2 was 75 0.; in Example 2 it was 150 C. The results are shown in the following table:

9. An O-alkylatlon process which comprises contacting a phenolic compound with an alkylating agent at an alkylatlng temperature below Example No 1 2 3 4 5 6 7 8 9 Alkylatable can.

pound:'

Kind PhenoL- Phenol p-Cresol 4-Methoxy- 2-t-Butyl-4- e-t-Butyl- Gatecliol Phenol Phenol.

Phenol. Me 1: h o x y- Phenol.

phenol. Gmms 47 47 54 62 45 75 55 47 47. lo'gutyltenagram 46 40 40.5--." 4 u ..'35 35 40 40.

a a ys rw oroacetieAcid Trlnltroi-xbellgzolc Oxallc Acid. Grams 6 6..' '8 B-Q 6 6 6 6 15, Product:

caisttltehiisoluble 22 21 24 20 15 16 10-15% 25 5.

are Y s Bcfiltlilig of 72-74-... 78-881. 100-115 "127-132 Ill-1151;- 95-97 7076 68-75.

are 1 PressurejmmHg. l9 17 .r 15 12 16 13 18 25.

1 This product was a tar rather than a simple ether 1 This product was soluble, which probably at 7, C-iwh eas at sietnrz retu eo no simple ethers were progluced from phenol and isobutylene whenusipg trichloroaceticacid as the telyst- N0 etiden of rin e k a was e ve i nyf. these e e ime I c aimas my int t n:

1. An Oalkylation process which comprises contacting a. phenolicicompound with an alkylating agentlat an alkylating temperature below about 150 C; 'in'the presence of a carboxylic acid alkylation catalyst.

2. An o alkylationprocess which comprises contacting'a phenoliccompound with an alkylating "agent at an alkylating temperature below about 150 0., apressure'such that substantially all of the reactants'are'in the liquid phase, and in the presence of a "carboxylic acid alkylation catalyst. A 7

3. The process'of claim 2 further characterized' in that the alkylating agent is an olefin,

4. The process of claiin '3 further characterized in thatthe olefin contains more than two carbonfatom's.

5. An' O alRyl'atiOn' process which comprises contacting a; phenolic compound with an alkylating agent'at' an alkylatlngteniperature below about 150 C; in "the presence'of a chlorcacetic acid alkylatiorl catalyst.

O alk yl'ation' process which comprises contacting a phenolic compound with an alkylating agent'at an alto/lath;g temperature below about 150 c a'pressure'such that substantially all of the reactants'are in the liquid phase, and in the presence ofza' chloroacetic acid alkylation catalyst. I

LThe process 'ofclaim 6 further characterized t the elky atln esent is a nflmfQ fi j .qffli lg lll urt characterized inthat thefoletln; contains more than two carbon atoms.

was due to the presence of an hydroxyl group on the nucleus in addition to the butoxy about C. in the.- presence of a nitrobenzoic i lk le o al st. 7

10. An O-alkylation process which comprises contacting a phenolic compound with an alkylating agent at an alkylating temperature below about 150 0,; a pressure such: that substantially all of the reactants are in. the liquid phase. and in the presence of a nitrobenzoic acid alkylation catalyst.

11. The process ofclaim' 10-furthercharaJcterized in that the alkylatlngagent'is an. olefin.

12. The process of claim 11 further'characterized in that the olefin' contains. more than two carbon atoms.

13. An O-alkylation process which comprises contacting a phenoliccompoundzwithan alkylating agent at an. alkylatingj temperature below about 150 C. in the presence of'trinitr'obenzoic acid.

14. An O-alkylation process which: comprises contacting a phenolic compound with an alkyl'ating agent at -an-alkylating'temperaturebelow aboit 150 C. in the presence of trichloro'acetic aci ROBERTH; ROSENWALD.

Rectum sf circle The I followingreferences are of record in the file of this patent:

UNITED sunsets-eerie Number Name Date 2,017,355 Rep'pe eta1. Oct. 15,1935 2,038,947 Maschfmeij'eret 'al. -Apr; 28; 1936 2,109,30 Niel'lwlahdet a1. Feb; 22,1938 2,147,256 Ipatiefi'et a1. Feb: 14, 1939 

